Method of producing a surface sleeve for a plate cylinder for printing purposes

Abstract

A surface sleeve for a rotogravure cylinder or an offset cylinder is produced by mounting a basic sleeve (20) on a supporting mandrel (10). Both the outer peripheral surface of the mandrel and the inner and outer surfaces of the basic sleeve are circularly cylindrical. On the nickel cylinder (20), a thin layer (21) of copper or nickel is deposited electrolytically, and on top of this layer an outer copper layer (22), preferably high-gloss copper, is deposited. In the case of rotogravure, this outer copper layer has a thickness which equals or slightly exceeds the desired maximum well depth of the printing pattern later to be made in the outer surface of the surface sleeve. In the case of offset printing, the outer copper layer is coated with a chrome layer in which the printing pattern is etched. After etching or engraving of a printing pattern in the outer surface of the sleeve, and after a possible chrome-plating of the etched or engraved surface, the free end parts of the surface sleeve are cut off, as the thickness of the metal layers there has become increased during the electrolytic deposits.

We claim: 
     
       1. A method of producing a surface sleeve for a plate cylinder, said method comprising, arranging a basic sleeve made from an electrically conductive material and having inner and outer circularly cylindrical peripheral surfaces, tightly around an outer circularly cylindrical peripheral surface of a supporting mandrel, electrolytically depositing an inner metal layer on the outer peripheral surface of the basic sleeve, electrolytically depositing an outer copper layer with a smooth substantially circularly cylindrical outer surface, on said inner metal layer, and cutting off opposite outer end portions of the sleeve after depositing the outer copper layer thereon. 
     
     
       2. A method according to claim 1, wherein the basic sleeve is made from metal. 
     
     
       3. A method according to claim 2, wherein said metal is nickel. 
     
     
       4. A method according to claim 3, wherein the inner metal layer is a layer of copper.   
     
     
       5. A method according to claim 4, wherein said copper is cyanide copper. 
     
     
       6. A method according to claim 3, wherein the inner metal layer is a layer of chloride nickel. 
     
     
       7. A method according to claim 5 or 6, wherein the thickness of said inner metal layer is about 2 μm. 
     
     
       8. A method according to claim 3, wherein the inner metal layer is formed by depositing nickel on the outer surface of the basic sleeve. 
     
     
       9. A method according to claim 8, wherein said nickel is chloride nickel. 
     
     
       10. A method according to claim 3 wherein the outer copper layer is deposited in a thickness which all over exceeds the desired well depth in a printing pattern so as to produce a surface sleeve for a rotogravure cylinder. 
     
     
       11. A method according to claim 3, further comprising coating the outer copper layer with a layer of chrome in which a printing pattern is later to be made, so as to produce a surface sleeve for an offset printing cylinder. 
     
     
       12. A method according to claim 11, wherein said chrome is matt hard chrome. 
     
     
       13. A method according to claim 3, wherein the basic sleeve arranged on the mandrel is a prefabricated sleeve. 
     
     
       14. A method according to claim 6, wherein the basic sleeve has a wall thickness of 0.1-0.2 mm. 
     
     
       15. A method according to claim 3, wherein the mandrel has an outer diameter slightly exceeding the inner diameter of the basic sleeve, the basic sleeve being expanded by means of a pressure fluid while it is being arranged on the mandrel. 
     
     
       16. A method according to claim 3, wherein depositing of the inner metal layer includes electrolytically depositing an initial metal layer on the outer surface of the basic sleeve in an electrolytic bath by providing a certain polarity, removing said initial layer by reversing said polarity, and finally depositing said inner metal layer. 
     
     
       17. A method according to claim 3, wherein the outer copper layer is deposited in a thickness of about 100-110 μm. 
     
     
       18. A method according to claim 3, wherein said inner and outer layers are electrolytically deposited by only partially immersing the mandrel with the basic sleeve arranged thereon into an electrolytic bath and rotating the mandrel at a substantially uniform speed while immersed in said bath. 
     
     
       19. A method according to claim 3, wherein the mandrel is a plate cylinder. 
     
     
       20. A method according to claim 3, wherein a printing pattern is provided in the outer peripheral surface of the surface sleeve produced prior to cutting off said opposite outer end portions. 
     
     
       21. A method of producing a surface sleeve for a plate cylinder, said method comprising, arranging the basic nickel sleeve having inner and outer circularly cylindrical peripheral surfaces tightly around an outer circularly cylindrical peripheral surface of a supporting mandrel, electrolytically depositing an inner metal layer on the outer surface of the basic sleeve, electrolytically depositing an outer copper layer with a smooth substantially circularly cylindrical outer surface on said inner metal layer, providing in said outer cyanide copper layer a rotogravure printing pattern comprising wells having a depth not exceeding the thickness of said outer layer, and cutting off opposite outer end portions of the surface sleeve so produced. 
     
     
       22. A method according to claim 21, wherein said inner metal layer is a layer of cyanide copper. 
     
     
       23. A method according to claim 21, wherein said inner metal layer is a layer of chloride nickel. 
     
     
       24. A method of producing a surface sleeve for an offset printing cylinder, said method comprising arranging a basic nickel sleeve having inner and outer circularly cylindrical peripheral surfaces tightly around an outer circularly cylindrical peripheral surface of a supporting mandrel, electrolytically depositing an inner metal layer on the outer peripheral surface of the basic sleeve, electrolytically depositing an outer copper layer with a smooth, substantially circularly cylindrical outer surface on said inner metal layer, coating said outer copper layer with a layer of matt hard chrome, providing an offset printing pattern in the outer peripheral surface of said chrome layer, and cutting off opposite outer end portions of the surface sleeve so produced. 
     
     
       25. A method according to claim 24, wherein said inner metal layer is a layer of cyanide copper. 
     
     
       26. A method according to claim 24, wherein said inner metal layer is a layer of chloride nickel. 
     
     
       27. A surface sleeve for a plate cylinder and comprising a basic nickel sleeve having inner and outer circularly cylindrical peripheral surfaces, an inner metal layer electrolytically deposited on the outer peripheral surface of the basic sleeve, and an outer copper layer with a smooth, substantially circularly cylindrical outer peripheral surface electrolytically deposited on said inner metal layer and having a rotogravure printing pattern provided therein, opposite outer end portions of the surface sleeve having been cut off after deposition of said outer copper layer thereon. 
     
     
       28. A surface sleeve for an offset printing cylinder and comprising a basic nickel sleeve having inner and outer circularly cylindrical peripheral surfaces, an inner metal layer electrolytically deposited on the outer peripheral surface of the basic sleeve, an outer copper layer with a smooth, substantially circularly cylindrical outer peripheral surface electrolytically deposited on said inner metal layer, and a coating of a matt hard chrome layer arranged on the peripheral surface of the outer copper layer and having an offset printing pattern provided thereon, opposite outer end portions of the surface sleeve having been cut off after deposition of said outer copper layer thereon.